The Five Universal Maxims of Islamic Law
(al-Qawa'id al-kulliyah al-khams)  compiled by Dr. Alan Godlas

"The five maxims were matters of consensus among all schools [of Muslim jurisprudence]."
(Umar Faruq 'Abd-Allah, Islam and the Cultural Imperative, note 12)

1) Matters shall be judged by their objectives. (Al-Umur bi-maqasidiha)
قاعدة: الأمور بمقاصدها
The First Principle: Matters are to be considered in light of their objectives

"There is evidence for this principle in the Prophet's statement: “Actions are but by intention, and a man will have only what he intended.” This hadith is of paramount importance. Indeed, some scholars have claimed that it has implications for at least seventy different branches of knowledge. Others have said about this hadith that it comprises a third of all knowledge."

The hadith used as a proof text and noted above is as follows:
ودليلها : قول النبي صلى الله عليه وسلم : « إنما الأعمال بالنيات

2) Certainty shall be removed by doubt. (Al-Yaqin la yazulu bi-al-shakk)
قاعدة: اليقين لا يزول بالشك

The Second Principle: That which is established with certainty is not removed by doubt

"This important principle is applied in every area of Islamic Law. It is estimated that the questions that are derived on its basis comprise three-fourths of all legal rulings. [Al-Suyûtî, al-Ashb wa al-Nazâ'ir (51). See also: al-Bûrnû, al-Wajîz fî al-Qawâ'id al-Fiqhiyyah al-Kulliyah (169)]

There is evidence for this principle in the Prophet's statement: “If one of you feels something in his stomach that makes him wonder if anything had passed from him, he should not leave the mosque until he either hears or smells something.” [ Sahîh Muslim ]

Al-Nawawî comments:

This hadîth sets forth a principle of Islam and a major axiom of Islamic Law, which is that things are legally assumed to remain as they are unless and until it is established with certainty that they are otherwise. Extraneous doubts are of no consequence. [ Sharh Sahîh Muslim (4/49)]"
The hadith used as a proof text above is as follows:
ودليلها : حديث : « لا ينصرف حتى يسمع صوتًا أو يجد ريحًا » .

3) Hardship shall bring alleviation. (Al-Mashaqqah tajlibu al-taysir)
قاعدة: المشقة تجلب التيسير

The Third Principle: The presence of difficulty requires that allowances be made to effect ease

"This principle embodies the fact that Islamic Law is built upon achieving ease and not upon imposing hardships. Whenever difficulties present themselves, the Law makes provisions to facilitate matters. The condition for such measures to be taken is that the difficulties are real and not imagined.

Allah says: “Allah intends for you ease and does not intend for you hardship.” [ Sûrah al-Baqarah : 185]

The Prophet (peace be upon him) said: “You have been sent forth to make things easy, not to impose difficulties.” [ Sahîh al-Bukhârî ]

`Â'ishah said: “The prophet (peace be upon him) had never been given the choice between two things except that he would choose the easiest of the two, so long as there was no sin in it.” [ Sahîh al-Bukhârî ]"

The Qur'anic proof text above is as follows:
ودليلها : قول الله تعالى : { وَمَا جَعَلَ عَلَيْكُمْ فِي الدِّينِ مِنْ حَرَجٍ} [الحج:78].
And the first of the two hadiths noted above is as follows:
 وقول الرسول صلى الله عليه وسلم : « بعثت بالحنيفية السَّمْحَة

4) Harm shall be removed. (Al-Darar yuzalu)

قاعدة: الضرر يزال

The Fourth Principle: Harm should be removed

"Islamic Law completely forbids that which causes harm. That which is harmful must be completely avoided whenever possible. When it is not possible, then the lesser of two evils should be perpetrated to avoid the greater. That which brings harm on a smaller scale is to be preferred to that which visits general harm to society. Likewise, the avoidance of harm takes priority over the attainment of some benefit.

Evidence for this principle can be found in the Prophet's statement: “There must be neither harm nor the imposition of harm.” [ Sunan al-Daraqutnî (3/77), al-Mustadrak (2/57), and Sunan al-Bayhaqî (6/69)]"

The above hadith used here as a proof-text is as follows:
ودليلها : حديث : « لا ضرر ولا ضرار » ، والضرر ما يكون بغير قصد ، والضرار ما يكون بقصد .

5) Cultural usage shall have the weight of law. (Al-' Adah muhakkamah)

قاعدة: العادة محكمة.

The Fifth Principle: Customary usage is the determining factor

"Custom refers to the prevailing practices of society with respect to their choice of words and their mode of action.
The principle that customary usage is the determining factor basically means that the customs of the people are recognized and acknowledged by Islamic Law as long as certain conditions are met. The most important of these conditions is that the custom in question does not violate the dictates of the sacred texts. Another is that the custom is indeed the prevailing practice in society and is applied in that society on a consistent basis. The third condition is that the custom must have been in effect at the time when a given activity was initially entered into without there having been any clear expression on the part of the concerned parties indicating something to the contrary. Finally, the custom must be of a nature that its application can be considered binding on the parties concerned.

Among the evidence for the recognition of custom in Islamic Law is the following hadith related by `Â'ishah:

Hind, the mother of Mu`âwiyah, said to the Prophet (peace be upon him): “Abû Sufyân (Hind's husband) is a tight-fisted man. Is there anything wrong if I take money from him secretly?”

The Prophet (peace be upon him) said: “Take for yourself and your children to suffice your needs according to what is customary.” [ Sahîh al-Bukhârî ]

Ibn Hajar al-`Asqalânî, in his commentary on Sahîh al-Bukhârî , observes: “He referred her to customary usage in a matter that was not precisely defined in Islamic Law.” [ Fath al-Bârî (4/407)]

Ibn Mas`ûd, the eminent Companion, said: “What the Muslims determine to be good is good with Allah.”
[ Musnad Ahmad ]

Ibn al-Qayyim writes:

On this basis, Islamic rulings are given throughout the ages. Whenever you find a custom in practice, you must take it into consideration, and whenever you find a custom has been abandoned, you must cease to consider it. You must not become unyielding all your life in adhering to what is recorded in the books. If someone comes to you from outside of your own region seeking a legal ruling, do not hold him to the customs of your land. Ask him about the customs of his own land and hold him to those and give your legal ruling accordingly. Do not apply the customs of your country that you find in your books. { I`lâm al-Muwaqqi`în (3/78)]"
The report of Ibn Mas'ud noted above and found in Musnad Ahmad is as follows:
ودليلها : قوله صلى الله عليه وسلم : « ما رآه المسلمون حسنًا فهو عند الله حسن »
Note on the sources:  The initial translations of the maxims have all been taken verbatim from Dr. Umar Faruq Abd-Allah, Islam and the Cultural Imperative, note 12, .
The Arabic can be found at Shaykh Muhammad ibn Husayn Ya'qub, al-Qawa'id al-fiqhiyah  (Arabic for Windows), at the end of which are proof-texts in Arabic for each of the five maxims (texts that I have inserted at the end of the English commentary for each maxim); and at  (Unicode simplified Arabic).
The commentary and the translations of the maxims just prior to each explanation have been taken verbatim from
Sheikh `Abd al-Rahmân b. Ahmad al-Jar`î , General Principles of Islamic Law and Their Practical Application for Islamic Work,